Patterns of Biofilm Succession on a Sheltered Rocky Shore in Hong Kong

Successional patterns are dependent on the nature of the substratum, water flow, concentrations of organics as well as the availability of bacteria, algal spores and invertebrate larvae in the coastal environment. Bacteria play an especially important role in biofilm formation as they are generally the earliest colonizers. In the present study, both winter and summer biofilm succession patterns were examined on glass coverslips inverted on experimental racks attached at two tidal levels on a sheltered shore in Hong Kong. In the succession, bacteria were followed by diatoms and cyanobacteria. Encrusting algae appeared in the late stages of the experiment (day 80 in summer and day 60 in winter). Colonization by bacteria was much slower in summer and their density remained low throughout the experimental period. The first appearance of diatoms and cyanobacteria, however, was more rapid in the summer. Bacteria and diatoms on the low-shore surfaces also had a faster succession rate than on the high-shore surfaces, suggesting that desiccation/aerial temperature are the causal factors for such differences.     

Antagonist-mediated down-regulation of toll-like receptors increases the prevalence of human papillomavirus infection in systemic lupus erythematosus

IntroductionPrevalence of an abnormal Papanicolaou smear was significantly increased in lupus patients in cross-sectional studies, associated with a higher prevalence of high-risk human papillomavirus (HPV) infection. The nucleic acid-specific Toll-like receptors (TLRs) locate at the endolysosomal compartments and trigger the induction of cytokines for the innate immune response. This study evaluated whether abnormal host innate immune response in lupus patients may enhance HPV persistence.MethodsProtein levels of TLRs 3, 7, 8 and 9 in cervical epithelial cells of lupus patients and controls with or without HPV infection were assessed using flow cytometry. Characteristics associated with the differential expression of TLRs in systemic lupus erythematosus (SLE) were elucidated. The effect and interferon-stimulated genes (ISGs) (ISG15 and Mx-1) gene expressions were then measured in oncogenic HeLa (HPV18), CaSki (HPV) and C33A (HPV negative) cell lines using flow cytometry and quantitative real-time PCR. Ex vivo productions of cytokines and interferon-gamma (IFN-γ) upon TLR ligands stimulations were subsequently measured using cytometric bead array and ELISA.ResultsFor subjects with HPV infection, levels of TLR3 and TLR7 were significantly lower in lupus patients compared with controls. Significantly decreased TLRs 7, 8 and 9 levels were observed in HPV-negative SLE compared to healthy controls. For SLE with and without HPV infection, TLR7 and 9 levels were significantly lower in infected SLE than those in HPV-negative patients. Independent explanatory variables associated with down-regulation of TLR7 level included HPV infection and a higher cumulative dose of prednisolone; while a higher cumulative dose of hydroxychloroquine and HPV infection were associated with down-regulation of TLR9 level. In cervical cell lines, TLRs 3, 7, 8, 9 protein levels and antiviral ISG15 and Mx-1 gene expressions were inhibited in two oncogenic HPV types. Functional data showed that the induction of pro-inflammatory cytokines by TLR ligands (R837, ssRNA and ODN2395) was greatly impaired in CaSki and HeLa than C33A cells.ConclusionsIn conclusion, prednisolone and TLR antagonist (hydroxychloroquine) may down-regulate protein levels of TLR7 and TLR9 in lupus patients, thereby decreasing the innate immune response against HPV infection. Upon infection, HPV further down-regulate TLR7 and 9 levels for viral persistence. Furthermore, reduction of nucleic acid-sensing TLRs 7, 8 and 9 in carcinogenic HPVs ensures that the expression of inducible pro-inflammatory cytokines is minimized to prevent the expression of antiviral ISGs (ISG15 and Mx-1) on a biologically relevant antiviral response.     

Computational prediction of essential genes in an unculturable endosymbiotic bacterium, Wolbachia of Brugia malayi

Background  

Wolbachia (wBm) is an obligate endosymbiotic bacterium of Brugia malayi, a parasitic filarial nematode of humans and one of the causative agents of lymphatic filariasis. There is a pressing need for new drugs against filarial parasites, such as B. malayi. As wBm is required for B. malayi development and fertility, targeting wBm is a promising approach. However, the lifecycle of neither B. malayi nor wBm can be maintained in vitro. To facilitate selection of potential drug targets we computationally ranked the wBm genome based on confidence that a particular gene is essential for the survival of the bacterium.     

Studies on the binding site of the galactose-specific agglutinin PA-IL from Pseudomonas aeruginosa

The binding properties of Pseudomonas aeruginosa agglutinin-I (PA-IL) with glycoproteins (gps) and polysaccharides were studied by both the biotin/avidin-mediated microtiter plate lectin-binding assay and the inhibition of agglutinin-glycan interaction with sugar ligands. Among 36 glycans tested for binding, PA-IL reacted best with two glycoproteins containing Galalpha1-->4Gal determinants and a human blood group ABO precursor equivalent gp, but this lectin reacted weakly or not at all with A and H active gps or sialylated gps. Among the mammalian disaccharides tested by the inhibition assay, the human blood group Pkactive Galalpha1-->4Gal, was the best. It was 7.4-fold less active than melibiose (Galalpha1-->6Glc). PA-IL has a preference for the alpha-anomer in decreasing order as follows: Galalpha1-->6 >Galalpha1-->4 >Galalpha1-->3. Of the monosaccharides studied, the phenylbeta derivatives of Gal were much better inhibitors than the methylbeta derivative, while only an insignificant difference was found between the Galalpha anomer of methyl- and p -NO2-phenyl derivatives. From these results, it can be concluded that the combining size of the agglutinin is as large as a disaccharide of the alpha-anomer of Gal at nonreducing end and most complementary to Galalpha1-->6Glc. As for the combining site of PA-IL toward the beta-anomer, the size is assumed to be less than that of Gal; carbon-6 in the pyranose form is essential, and hydrophobic interaction is important for binding.      

Detoxications in peripatus. Sulphate, phosphate and histidine conjugations

Phenols were detoxified in the Onycophoran Peripatoides novaezealandiae by conjugation with sulphuric acid and phosphoric acid, but no evidence for a glycoside detoxication could be found. [(14)C]Benzoic acid was metabolized in 24h to N(2)-benzoyl-l-histidine, which was identified by electrophoresis, chromatography and dilution analysis. Similar conjugates were formed with p-aminobenzoic acid and p-nitrobenzoic acid. In longer-duration experiments further unidentified metabolites were formed, two of which appeared to result from the further metabolism of the histidine conjugate.     

Altered glial function causes neuronal death and increases neuronal susceptibility to 1-methyl-4-phenylpyridinium- and 6-hydroxydopamine-induced toxicity in astrocytic/ventral mesencephalic co-cultures

Altered glial function in the substantia nigra in Parkinson's disease may lead to the release of toxic substances that cause dopaminergic cell death or increase neuronal vulnerability to neurotoxins. To investigate this concept, we examined the effects of subjecting astrocytes to lipopolysaccharide (LPS)-induced activation alone or combined with L-buthionine-[S,R]-sulfoximine-induced glutathione depletion or inhibition of complex I activity by 1-methyl-4-phenylpyridinium (MPP+) on the viability of primary ventral mesencephalic neurones or susceptibility to MPP+ and 6-hydroxydopamine (6-OHDA) in co-cultures. LPS-activated astrocytes caused neuronal death in a time-dependent manner, but glutathione-depleted or complex I-inhibited astrocytes had no effect on neuronal viability. The neurotoxicity of LPS-activated astrocytes was inhibited by the inducible nitric oxide synthase inhibitor aminoguanidine, by the nitric oxide scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and by reduced glutathione (GSH). MPP+-induced neuronal death was greater in ventral mesencephalic cultures previously cultured with LPS-activated, glutathione-depleted, or complex I-inhibited astrocytes compared with co-cultures containing normal astrocytes. The increased neuronal susceptibility to MPP+ caused by LPS-activated or complex I-inhibited astrocytes and glutathione-depleted astrocytes was inhibited by the NMDA/glutamate antagonist MK-801 and by GSH, respectively. Neuronal death caused by 6-OHDA was increased in ventral mesencephalic cultures previously cultured with LPS-activated and glutathione-depleted, but not complex I-inhibited astrocytes, compared with co-cultures containing normal astrocytes. Treatment of co-cultures with GSH prevented the increased neuronal susceptibility to 6-OHDA. These findings suggest that glial dysfunction may cause neuronal death or render neurones susceptible to toxic insults via a mechanism involving the release of free radicals and glutamate. Such a mechanism may play a role in the development or progression of nigrostriatal degeneration in Parkinson's disease.     

Effect of self-association on the structural organization of partially folded proteins: inactivated actin

The propensity to associate or aggregate is one of the characteristic properties of many nonnative proteins. The aggregation of proteins is responsible for a number of human diseases and is a significant problem in biotechnology. Despite this, little is currently known about the effect of self-association on the structural properties and conformational stability of partially folded protein molecules. G-actin is shown to form equilibrium unfolding intermediate in the vicinity of 1.5 M guanidinium chloride (GdmCl). Refolding from the GdmCl unfolded state is terminated at the stage of formation of the same intermediate state. An analogous form, known as inactivated actin, can be obtained by heat treatment, or at moderate urea concentration, or by the release of Ca(2+). In all cases actin forms specific associates comprising partially folded protein molecules. The structural properties and conformational stability of inactivated actin were studied over a wide range of protein concentrations, and it was established that the process of self-association is rather specific. We have also shown that inactivated actin, being denatured, is characterized by a relatively rigid microenvironment of aromatic residues and exhibits a considerable limitation in the internal mobility of tryptophans. This means that specific self-association can play an important structure-forming role for the partially folded protein molecules.     

Systems and organismal aspects of phosphorus remineralization

During a six-month study at Lake George, N.Y., zooplankton contributed an average of 19.4% of the phosphate required for algal photosynthesis. Values ranged from 44.1% prior to the unimodal phytoplankton pulse to 4.6% during the phytoplankton bloom. Copepods accounted for a large percentage (21–68%) of the SRP recycled during the growing season examined, whereas, the cladocera provided only a small percentage of remineralization (6.9%).Contribution No. 315 from the Eastern Deciduous Forest Biome, U. .-IBP, Research supported by the Eastern Diciduous Forest Biome U.S.-IBP, funded by the National Science Foundation under interagency agreement AG-199. DEB 76-00761 with the U.S. Department of Energy — Oak Ridge National Laboratory.